3) Go to Options, Configure Controller Plugin. Then, select and configure an input plugin to use. (The netplay plugin relies on another input plugin to do the actual work of reading input from the keyboard/controller.) Make sure one and only one controller is plugged in for each player that will be playing locally (at the same computer). To be a spectator, unplug all controllers.

4) Select a game to play. Send the save file for that game to each player you plan to play with. The save file is located in the "Save" folder by default. If each player does not have the exact same save file, the emulators will probably desync. (If I could, I would have the netplay plugin automatically distribute the save file to everyone else, but it is impossible for an input plugin to know where the save files are located.)

5) Open the game. The netplay plugin window will appear. One person will host the server and everyone else will connect to the host.

The host needs to type the "/server port" command in the box at the bottom and hit enter, where "port" is the port number the server will listen on for connections. The port can be any number between 1 and 65535. A message from a firewall may appear. Be sure to click Allow. Also, if the host is behind an NAT (home router), the port will needed to be forwarded.

Everyone else needs to use the command "/connect host port" to connect to the host, where "host" is the IP address of the host and "port" is the port that the host chose to host the server.

(Note: If anyone is using WiFi (excluding spectators), the game may be laggy unless they have a strong signal with low interference. You're better off using an ethernet cable.)

6) Use the "/name name" command to change your name. The name you choose will be remembered next time you play.

7) Use the "/start" command to start the game.

8) Use the "/lag lag" command to change the lag of the game, where "lag" is the number of frames of delay between when you press a button and when that information reaches the game. Choose the lowest number possible. If you set the lag too low, the game will run slow, especially if there is a lot of latency on the connection between the players. If you set the lag too high, the game will be difficult to play.